Being in this section I assume you're looking for a 73-79 truck. Front Discs and shoulder belts became standard across the board in 76...so that's where I'd start. FE's are typically more expensive to work with, that's what you'd get in 76 (unless 2wd and 460). So that moves you to strictly looking at 77-79's. If you're looking 4x4, the 77.5-79 250's are far superior to the 73-77.5 trucks. From there, it's a matter of aesthetic preference with grill and headlight orientation, body color, and condition of the vehicle. All of them are stupid easy to work on and self-teach.

Being in this section I assume you're looking for a 73-79 truck. Front Discs and shoulder belts became standard across the board in 76...so that's where I'd start. FE's are typically more expensive to work with, that's what you'd get in 76 (unless 2wd and 460). So that moves you to strictly looking at 77-79's. If you're looking 4x4, the 77.5-79 250's are far superior to the 73-77.5 trucks. From there, it's a matter of aesthetic preference with grill and headlight orientation, body color, and condition of the vehicle. All of them are stupid easy to work on and self-teach.

I wouldn't...with the 80's you start talking ttb front axles for 4x4's...86ish, you start seeing the move to efi, which is fine, but most think working on a carb is easier.

Realistically, to answer this question, you'll need to establish a couple things:
1) Budget
2) What you're capable of fixing yourself, because buying anything 20+ years old is going to require work.
3) What characteristics are important to you

That comes down to what you want. If you want the look of the late 70's trucks, and that is the main focus, stick with them. Parts are readily available so that is not an issue. They are more sought after, so it can drive the initial investment up but that also is highly dependent on where you are located.

The 80's trucks have their pluses and minuses as well, so it again comes back to what exactly is drawing you to any particular generation.